1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor element. In particular, the present invention relates to a method of manufacturing a semiconductor element having wiring lines with improved reliability.
2. Description of the Related Art
Highly integrated semiconductor elements may require reliable wiring lines. Such wiring lines may be made of materials, such as, for example, aluminum or copper. Copper may have a relatively high melting point as compared to aluminum, and therefore, may exhibit superior electro-migration, i.e., “EM,” and stress-migration, i.e., “SM,” characteristics and low relative resistance properties.
A conventional method of forming such wiring lines in a semiconductor element may be performed as follows. An interlayer insulating film and a lower metal wiring layer may be formed sequentially on a semiconductor substrate and an opening may be etched in the interlayer insulating film using a photoresist pattern as an etching mask. Next, the photoresist pattern may be removed by plasma ashing. Subsequently, any impurities generated during dry etching and plasma ashing, metal oxides formed on the lower metal wiring layer, charge-carrying components generated by plasma and the like may be removed from the opening by wet cleaning. Finally, an upper wiring layer may be formed by filling a conductive material into the opening of the interlayer insulating film to form wiring lines of the semiconductor element.
The conventional wet cleaning process for removing impurities, metal-oxides, and charge-carrying components may include application of a cleaning solution into the opening and performance of a washing process therein with deionized water. However, when a washing process using the deionized water is performed, the lower metal wiring layer may be exposed, thereby triggering oxidation or metal extraction therefrom. An oxidation or metal extraction from the lower metal wiring layer may generate voids therein during formation of the upper metal wiring layer, and, thereby, reduce overall reliability of the semiconductor element.
Accordingly, there exists a need for an improved method of forming a semiconductor element capable of providing reduced oxidation and metal extraction during formation of metal wiring layers thereof.